My second batch of kolsch has been in bottles about a week or a week and a half. I tried one last night with some trepidation and man, was I pleasantly surprised! It was already good.
My first batch was another story. It didn't get good until it was about 6 weeks old. Then, when I had about a six-pack left and it was about 5 months old it REALLY got good.
Although this is really old news to most people here, I have really seen better results after getting a secondary carboy. I try to follow the 1-2-3 rule, but I find that I tend to be a bit slow on getting the beer bottled, so it tends to stay in the secondary a little longer than 2 weeks (ok, sometimes a LOT longer). My last two batches were drinkable in the bottles very quickly. They were actually a bit carbonated coming out of the secondary. The other thing that has really improved is clarity. My single carboy brews would get really clear, but only after they got to be 4-5 months old. Now with a secondary they are just as clear after about two weeks in bottles.